Unbaffled – NOS Carver Drivers

I have been purchasing used Carver amazing drivers for some time.  Today I put my collection of original hex cone drivers to the test in a full six driver dipole configuration.  The drivers are connected in two sets of three wired in series, the two sets then wired in parallel.  Each driver has a DCR of 3.5 ohms, so the net impedance is a reasonable 5.3 ohms.

2016-03-05 6x12 2mGPTest configuration is a ground plane measurement at 2 meters.  I also did a similar measurement with the 4×15″ driver dipole panel I built with Goldwood drivers.

Compare_0dBWI know what you are thinking, these are the same speaker measured twice.  Nope!  I have added some silicon to the cones of the 15″ drivers to decrease their resonance to 24 Hz / raise their Qts to about 3.5.  They are very close in specs to the original Carver drivers at 24 Hz / Qts = 3.0.  Note the baffles are even different – the baffle is 24″ wide for the 4×15 and 15″ wide for the 6×12 – so maybe that compensates a little for the small difference in Qts.

2016-03-05 4x15 close micClose_mic_15For reference, consider a close mic measurement of one of the 15″ drivers (blue) compared to the array 2 meter ground plane measurement (green).  You can see that the dipole bass cancelation is -15 dB at 24 Hz.  You can also see multiple dips at 35, 57, 121, and 141 Hz.  I had the speakers facing into the garage, so I am wondering if these dips were due to the finite baffle, or a garage Helmholtz resonance.

So another test I tried was to put the 6×12″ on its side and compare to the standing array.

2016-03-05 6x12 on side

A little bit of gain, but otherwise the same response.